The present invention concerns a lock nut (1) for a bearing, especially a wheel bearing of vehicles, wherein the bearing has a universal shaft which introduces the torque across a splining, and a flange, which is axially fastened to the universal shaft by a screw connection.
A nut of this kind is known from DE 195 43 436 C2. This document discloses a sleevelike threaded nut, which is used on a universal shaft of motor vehicle wheels to secure a wheel flange in a wheel bearing. In this case, the sleevelike threaded nut is screwed onto a threaded journal formed on the universal shaft and its axially resilient clamping flange lies against the wheel flange with prestress. The clamping flange passes into a hexagonal recess, which serves to fasten the threaded nut onto the threaded journal of the shaft. Notches are provided at the outer circumference of the threaded portion of the nut, which engage in a splining to secure the threaded nut, transferring the torque from the universal shaft to the wheel flange. In any case, the prestressing force of the bearing is produced by forming the inner end of the hub shaft provided on the wheel flange radially outward into a bead, which thrusts against the roller bearing races that are shoved onto the hub shaft, as is also described in patent DE 4,339,847 C1. This kind of nut serves only as a captive device with slight clamping force, so that the described configuration as a sheet metal part is sufficient.
Practice has shown that the familiar sleevelike threaded nut does not meet the requirements for the clamping force, due to the constantly occurring load changes at the wheel bearing, especially when braking and accelerating the vehicle in curves. The clamping force of this threaded nut produced as a deep-drawn sheet metal part can slacken considerably, which is not acceptable for safety reasons. Furthermore, because of the flexible design of the clamping flange of the sleevelike threaded nut, moisture cannot be reliably prevented from getting into the region of the splining. Thus, the splining may become corroded, so that a reliable transmission of the torque is no longer guaranteed.
The tooling expenses and the production costs are considerable for the sleevelike threaded nut manufactured as a deep-drawn part.